Hydrogen Combustion Risk and Core Debris Coolability (HYBCIS): HYBCIS summary report

The HYBCIS project has focused on two different topics in the area of severe accident research: the coolability of porous core debris beds and the risk of hydrogen combustion in containments. A new test facility, COOLOCE has been designed and built for experimental investigations of coolability of porous particle beds with a flexible geometry. The main objective of the experiments is to compare the coolability of a heap-like (conical) particle bed configuration to that of an evenly-distributed cylindrical particle bed. The first experiments with a conical particle bed have been performed. Along with the experimental work, simulation tools are applied to model the phenomenon. The assessment of hydrogen risk in containments consists of computational analysis addressing hydrogen distribution, mitigation and combustion. In the present project, simulations of slow hydrogen deflagrations have been performed using the FLUENT CFD software. The simulation work is closely connected to the OECD THAI research project whose follow-up has been done within the HYBCIS project.